Sinter powder (sp) containing a semi-crystalline terephthalate polyester

ABSTRACT

The present invention relates to a sinter powder (SP) comprising at least one semicrystalline terephthalate polyester (A) which is prepared by reacting at least one aromatic dicarboxylic acid (a) and at least two aliphatic diols (b1) and (b2), where the aliphatic diol (b1) is neopentyl glycol. The present invention further relates to a method of producing the sinter powder (SP), and to a method of producing a shaped body by sintering the sinter powder (SP). The present invention further relates to the shaped body obtainable by the sintering. The present invention also relates to the use of the sinter powder (SP) in a sintering method.

The present invention relates to a sinter powder (SP) comprising atleast one semicrystalline terephthalate polyester (A) which is preparedby reacting at least one aromatic dicarboxylic acid (a) and at least twoaliphatic diols (b1) and (b2), where the aliphatic diol (b1) isneopentyl glycol. The molar ratio of component (a) to component (b1) inthe preparation of the at least one semicrystalline terephthalatepolyester (A) is in the range from 1:0.15 to 1:0.65 [mol/mol]. Thepresent invention further relates to a method of producing the sinterpowder (SP), and to a method of producing a shaped body by sintering thesinter powder (SP). The present invention further relates to the shapedbody obtainable by the sintering. The present invention also relates tothe use of the sinter powder (SP) in a sintering method.

The rapid provision of prototypes is a problem often addressed in recenttimes. One method which is particularly suitable for this “rapidprototyping” is selective laser sintering (SLS). This involvesselectively exposing a plastic powder in a chamber to a laser beam. Thepowder melts; the molten particles coalesce and resolidify. Repeatedapplication of plastic powder and subsequent exposure to a laser allowsmodeling of three-dimensional shaped bodies.

The method of selective laser sintering for producing shaped bodies frompulverulent polymers is described in detail in patent specificationsU.S. Pat. No. 6,136,948 and WO 96/06881.

Novel variants of selective laser sintering are high-speed sintering(HSS) or what is called multijet fusion technology (MJF) from HP. Inthis method, by spray application of an infrared-absorbing ink onto thecomponent cross section to be sintered, followed by melting with aninfrared source, a higher processing speed is achieved compared toselective laser sintering.

A factor of particular significance in high-speed sintering or multijetfusion technology and also in selective laser sintering is the sinteringwindow of the sinter powder. This should be as broad as possible inorder to reduce warpage of components in the laser sintering operation.For this reason, particularly the processing of semicrystallineterephthalate polyester-based sinter powders is frequently difficultsince semicrystalline terephthalate polyesters have a narrow sinteringwindow and crystallize very quickly, and so components having highwarpage are frequently obtained.

A further important point in high-speed sintering or multijet fusiontechnology and also in selective laser sintering is the level of themelting temperature of the sinter powder. This should not be more than200° C., in order firstly to minimize the energy required in thesintering operation, and secondly to assure sinterability of the sinterpowder in standard laser sintering systems, which have a maximum buildspace temperature of about 200° C. Since pure polybutylene terephthalate(PBT), for example, has a melting temperature of about 220° C., theprocessing of pure polybutylene terephthalate powders in standard lasersintering systems is generally very difficult. The same also applies,for example, to pure polyethylene terephthalate (PET) powder, since purepolyethylene terephthalate likewise has a high melting temperature ofmore than 250° C.

To increase the sintering window and/or to lower the meltingtemperature, the sinter powders based on semicrystalline terephthalatepolyesters are therefore typically mixed with further, preferablyamorphous, polymer powders, or sinter powders based on terephthalatecopolymers are used. However, the shaped bodies produced from thesesinter powders to date frequently have inadequate mechanical properties,for example too low a tensile modulus of elasticity or too low a tensilestrength.

The article “Production and Processing of a spherical polybutyleneterephthalate powder for laser sintering” by Rob G. Kleijnen, ManfredSchmid and Konrad Wegener (Applied Sciences, 2019, 9, 1308) describesthe production of a spherical PBT powder and the use thereof in aselective laser sintering process. The shaped bodies produced from thePBT powder have significant warpage and inadequate mechanicalproperties, such as a low tensile modulus of elasticity, low elongationat break and low tensile strength.

The article “Comparison of crystallization characteristics andmechanical properties of poly(butylene terephthalate) processed by lasersintering and injection molding” by S. Arai et al. (Materials andDesign, 2017, 113, 214) describes the production of a powder from a PBTcopolymer comprising 10 mol % of isophthalic acid. The powder has amelting temperature of about 208° C. and may be sintered in a selectivesintering process at a powder bed temperature of 190° C. to give shapedbodies.

US 2015/0259530 discloses a composition comprising a semicrystalline PETcopolyester, a glycol-modified amorphous PET and an impact modifier foruse in a sintering method.

U.S. Pat. No. 8,247,492 describes sinterable powder compositionscomprising a semicrystalline aromatic polyester and an amorphousaromatic polyester. The semicrystalline aromatic polyester is preparedby reaction of terephthalic acid, isophthalic acid, butane-1,4-diol andpropane-1,3-diol; the amorphous aromatic polyester is prepared byreaction of terephthalic acid, isophthalic acid and ethylene glycol. Thepowder compositions have melting temperatures in the range from 145 to150° C. and may be sintered to give shaped bodies having a modulus ofelasticity of 1000 MPa and a tensile strength of 20 MPa.

WO 2019/177850 describes a build material for additive manufacturingapplications, comprising a build composition in powder form, wherein thebuild composition comprises a semicrystalline polymer. Thesemi-crystalline polymer may be a polyester or copolyester and maycomprise terephthalic acid radicals, and neopentyl glycol as glycolradical.

A disadvantage of the semicrystalline terephthalate polyester-basedsinter powders described in the prior art for production of shapedbodies by selective laser sintering is that the sintering window of thesinter powders is frequently insufficiently broad, such that the shapedbodies frequently warp during production by selective laser sintering.This warpage virtually rules out use or further processing of the shapedbodies. Even during the production of the shaped bodies, the warpage canbe so severe that further layer application is impossible and thereforethe production process has to be stopped. If shaped bodies are producedfrom sinter powders that comprise a further polymer as well as thesemicrystalline terephthalate polyester, or that comprise theterephthalate polyester in the form of a copolymer, these shaped bodiesfrequently have unsatisfactory mechanical properties, such as a lowtensile modulus of elasticity and/or low tensile strength.

It is thus an object of the present invention to provide a sinter powderwhich, in a method of producing shaped bodies by laser sintering, hasthe aforementioned disadvantages of the sinter powders and methodsdescribed in the prior art only to a lesser degree, if at all. Thesinter powder and the method should be producible and performable in avery simple and inexpensive manner.

This object is achieved by a sinter powder (SP) comprising the followingcomponents (A) and optionally (B), (C) and/or (D):

-   (A) at least one semicrystalline terephthalate polyester which is    prepared by reacting at least components (a) and (b):    -   (a) at least one aromatic dicarboxylic acid and    -   (b) at least two aliphatic diols (b1) and (b2), where the        aliphatic diol (b1) is neopentyl glycol,-   (B) optionally at least one further polymer,-   (C) optionally at least one additive and/or-   (D) optionally at least one reinforcer, where

the molar ratio of component (a) to component (b1) in the preparation ofthe at least one semicrystalline terephthalate polyester (A) is in therange from 1:0.15 to 1:0.65 [mol/mol].

It has been found that, surprisingly, the sinter powder (SP) of theinvention has distinctly slowed crystallization kinetics and hence sucha broadened sintering window (W_(SP)) or such a broadened processingtemperature range that the shaped body produced by sintering the sinterpowder (SP) has distinctly reduced warpage, if any. Furthermore, themelting temperature of the sinter powder (SP) of the invention is muchlower compared to the melting temperature of sinter powders from theprior art comprising a semicrystalline terephthalate polyester, and sothe sinter powder (SP) of the invention can be used without difficultyin all standard laser sintering systems having maximum build spacetemperatures of 200° C. Moreover, the energy demand on sintering isdistinctly smaller by virtue of the lowered melting temperature.

Furthermore, it has been found that, surprisingly, the shaped bodiesproduced from the sinter powder of the invention have very goodmechanical properties, such as high tensile modulus of elasticity andhigh tensile strength.

In addition, degradation of the sinter powder (SP) used in the processof the invention is low even after thermal treatment. This means thatsinter powder (SP) not melted in the production of the shaped body canbe reused. Even after several laser sintering cycles, the sinter powder(SP) has similarly advantageous sintering properties to those in thefirst sintering cycle.

Sinter Powder (SP)

According to the invention, the sinter powder (SP) comprises at leastone semicrystalline terephthalate polyester as component (A), optionallyat least one further polymer as component (B), optionally at least oneadditive as component (C), and optionally at least one reinforcer ascomponent (D).

In the context of the present invention the terms “component (A)” and“at least one semicrystalline terephthalate polyester” are usedsynonymously and therefore have the same meaning.

The same applies to the terms “component (B)” and “at least one furtherpolymer”. These terms are likewise used synonymously in the context ofthe present invention and therefore have the same meaning.

Accordingly, the terms “component (C)” and “at least one additive”, andthe terms “component (D)” and “at least one reinforcer”, are also eachused synonymously in the context of the present invention and have thesame meaning.

The sinter powder (SP) may comprise component (A) and optionallycomponents (B), (C) and (D) in any desired amounts.

For example, the sinter powder (SP) comprises in the range from 15% to100% by weight of component (A), in the range from 0% to 25% by weightof component (B), in the range from 0% to 20% by weight of component (C)and in the range from 0% to 40% by weight of component (D), based ineach case on the sum total of the percentages by weight of components(A) and optionally (B), (C) and (D), preferably based on the totalweight of the sinter powder (SP).

In a preferred embodiment, the sinter powder (SP) comprises in the rangefrom 15% to 95% by weight of component (A), in the range from 0% to 25%by weight of component (B), in the range from 0% to 20% by weight ofcomponent (C) and in the range from 5% to 40% by weight of component(D), based in each case on the sum total of the percentages by weight ofcomponents (A) and (D) and optionally (B) and (C), preferably based onthe total weight of the sinter powder (SP).

In an alternative preferred embodiment, the sinter powder (SP) comprises

in the range from 15% to 98.9% by weight, preferably in the range from17% to 92% by weight, of component (A),

in the range from 1% to 25% by weight, preferably in the range from 2%to 23% by weight, of component (B),

in the range from 0.1% to 20% by weight, preferably in the range from 1%to 20% by weight, of component (C) and

in the range from 0% to 40% by weight, preferably in the range from 5%to 40% by weight, of component (D),

based in each case on the sum total of the percentages by weight ofcomponents (A), (B), (C) and optionally (D), preferably based on thetotal weight of the sinter powder (SP).

The percentages by weight of components (A) and optionally (B), (C) and(D) typically add up to 100% by weight.

The sinter powder (SP) comprises particles. These particles have, forexample, a size (D50) in the range from 10 to 250 μm, preferably in therange from 15 to 200 μm, more preferably in the range from 25 to 90 μmand especially preferably in the range from 40 to 80 μm.

The present invention therefore also provides a sinter powder (SP),wherein the sinter powder has a median particle size (D50) in the rangefrom 10 to 250 μm.

The sinter powder (SP) of the invention has, for example,

a D10 in the range from 10 to 60 μm,

a D50 in the range from 25 to 90 μm and

a D90 in the range from 50 to 150 μm.

Preferably, the sinter powder (SP) of the invention has

a D10 in the range from 20 to 50 μm,

a D50 in the range from 40 to 80 μm and

a D90 in the range from 80 to 125 μm.

The present invention therefore also provides a sinter powder (SP),wherein the sinter powder (SP) has

a D10 in the range from 10 to 60 μm,

a D50 in the range from 25 to 90 μm and

a D90 in the range from 50 to 150 μm.

In the context of the present invention, the “D10” is to be understoodas meaning the particle size at which 10% by volume of the particlesbased on the total volume of the particles are smaller than or equal tothe D10 and 90% by volume of the particles based on the total volume ofthe particles are larger than the D10. By analogy, the “D50” isunderstood to mean the particle size at which 50% by volume of theparticles based on the total volume of the particles are smaller than orequal to the D50 and 50% by volume of the particles based on the totalvolume of the particles are larger than the D50. Correspondingly, the“D90” is understood to mean the particle size at which 90% by volume ofthe particles based on the total volume of the particles are smallerthan or equal to the D90 and 10% by volume of the particles based on thetotal volume of the particles are larger than the D90.

To determine the particle sizes, the sinter powder (SP) is suspended ina dry state using compressed air or in a solvent, for example water orethanol, and this suspension is analyzed. The D10, D50 and D90 aredetermined by means of laser diffraction using a Malvern MasterSizer3000. Evaluation is by means of Fraunhofer diffraction.

The sinter powder (SP) has preferably been heat treated.

Preferably, the sinter powder is heat-treated at a temperature T_(T) inthe range from 80 to 140° C., more preferably in the range from 85 to135° C., and most preferably in the range from 100 to 130° C.

In a preferred embodiment, the sinter powder (SP) is heat treated withina period in the range from 1 to 20 hours. The heat treatment ispreferably effected in a drying cabinet under reduced pressure or underprotective gas. The protective gas used is, for example, nitrogen.

The sinter powder (SP) typically has a melting temperature (T_(M)) inthe range from 130 to 210° C. Preferably, the melting temperature(T_(M)) of the sinter powder (SP) is in the range from 135 to 205° C.and especially preferably in the range from 140 to 180° C.

The melting temperature (T_(M)) is determined in the context of thepresent invention by means of differential scanning calorimetry (DSC).It is customary to measure a heating run (H) and a cooling run (K), eachwith a constant heating rate or cooling rate in the range from 5 to 25K/min, preferably at a constant heating rate or cooling rate in therange from 5 to 15 K/min. This gives a DSC diagram as shown by way ofexample in FIG. 1 . The melting temperature (T_(M)) is then understoodto mean the temperature at which the melting peak of the heating run (H)of the DSC diagram has a maximum.

The sinter powder (SP) typically also has a crystallization temperature(T_(C)) in the range from 70 to 130° C. Preferably, the crystallizationtemperature (T_(C)) of the sinter powder (SP) is in the range from 75 to125° C. and especially preferably in the range from 80 to 120° C.

The crystallization temperature (T_(C)) is determined in the context ofthe present invention by means of differential scanning calorimetry(DSC). It is customary here to measure a heating run (H) and a coolingrun (K), each with a constant heating rate or cooling rate in the rangefrom 5 to 25 K/min, preferably at a constant heating rate or coolingrate in the range from 5 to 15 K/min. This gives a DSC diagram as shownby way of example in FIG. 1 . The crystallization temperature (T_(C)) isthen the temperature at the minimum of the crystallization peak of theDSC curve.

The sinter powder (SP) typically also has a sintering window (W_(SP)).

If heating run (H) and cooling run (K) are measured with a constantheating rate and cooling rate in the range from 5 to 15 K/min, thesintering window (W_(SP)), as described below, is the difference betweenthe onset temperature of melting (T_(M) ^(onset)) and the onsettemperature of crystallization (T_(C) ^(onset)). The onset temperatureof melting (T_(M) ^(onset)) and the onset temperature of crystallization(T_(C) ^(onset)) are determined as described hereinafter with regard tostep c).

The sintering window (W_(SP)) of the sinter powder (SP) is then, forexample, in the range from 10 to 40 K (kelvin), more preferably in therange from 15 to 35 K, particularly preferably in the range from 20 to33 K and especially preferably in the range from 22 to 33 K.

If heating run (H) and cooling run (K) are measured with a constantheating rate and cooling rate in the range from 15 to 25 K/min, thesintering window (W_(SP)) in the context of the present invention is thedifference between the onset temperature of melting (T_(M) ^(onset)) andthe glass transition temperature (T_(G)). The onset temperature ofmelting (T_(M) ^(onset)) and the glass transition temperature (T_(G))are determined as described hereinafter with regard to step c).

The sintering window (W_(SP)) of the sinter powder (SP) in that case ismuch broader; it is then, for example, in the range from 20 to 80 K,more preferably in the range from 30 to 70 K.

In addition, the sinter powder (SP) typically has a first enthalpy offusion ΔH1_((SP)) and a second enthalpy of fusion ΔH2_((SP)), where theenthalpies of fusion ΔH1_((SP)) and ΔH2_((SP)) of the sinter powder (SP)are proportional to the area under the melting peak of the first heatingrun (H1) and of the second heating run (H2) in the DSC diagramrespectively. The following general rule is applicable here: The greaterthe difference between the first enthalpy of fusion ΔH1_((Sp)) and thesecond enthalpy of fusion ΔH2_((SP)), the slower the crystallization andthe broader the sintering window (W_(SP)). In the context of the presentinvention, the difference between the first enthalpy of fusionΔH1_((SP)) and the second enthalpy of fusion ΔH2_((SP)) is preferably atleast 10 J/g, more preferably at least 12 J/g.

The sinter powder (SP) can be produced by any methods known to thoseskilled in the art. For example, the sinter powder is produced bygrinding, by precipitation, by melt emulsification, by spray extrusionor by micropelletization. The production of the sinter powder (SP) bygrinding, by precipitation, by melt emulsification, by spray extrusionor by micropelletization is also referred to in the context of thepresent invention as micronization.

If the sinter powder (SP) is produced by precipitation, components (A)and optionally (B), (C) and (D) are typically mixed with a solvent, andcomponent (A) and optionally component (B) are optionally dissolved inthe solvent while heating to obtain a solution. The sinter powder (SP)is subsequently precipitated, for example by cooling the solution,distilling the solvent out of the solution or adding a precipitant tothe solution.

The grinding can be conducted by any methods known to those skilled inthe art; for example, components (A) and optionally (B), (C) and (D) areintroduced into a mill and ground therein.

Suitable mills include all mills known to those skilled in the art, forexample classifier mills, opposed jet mills, hammer mills, ball mills,vibratory mills or rotor mills such as pinned disk mills and whirlwindmills.

The grinding in the mill can likewise be effected by any methods knownto those skilled in the art. For example, the grinding can take placeunder inert gas and/or while cooling with liquid nitrogen. Cooling withliquid nitrogen is preferred. The temperature in the grinding is asdesired; the grinding is preferably performed at liquid nitrogentemperatures, for example at a temperature in the range from −210 to−195° C. The temperature of the components on grinding in that case is,for example, in the range from −40 to −30° C.

Preferably, the components are first mixed with one another and thenground.

Preferably, at least component (A) is in the form of a pelletizedmaterial prior to the micronization. As well as component (A), it isoptionally also possible for components (B), (C) and (D) to be in theform of a pelletized material. The pelletized material may, for example,be spherical, cylindrical or ellipsoidal. In the context of the presentinvention, in a preferred embodiment, a pelletized material comprisingcomponents (A) and optionally (B), (C) and (D) in premixed form is used.

The method of producing the sinter powder (SP) in that case preferablycomprises the steps of

-   a) mixing components (A) and optionally (B), (C) and/or (D):    -   (A) at least one semicrystalline terephthalate polyester which        is prepared by reacting at least components (a) and (b):        -   (a) at least one aromatic dicarboxylic acid and        -   (b) at least two aliphatic diols (b1) and (b2), where the            aliphatic diol (b1) is neopentyl glycol,    -   (B) optionally at least one further polymer,    -   (C) optionally at least one additive and/or    -   (D) optionally at least one reinforcer,    -   in an extruder to obtain an extrudate (E) comprising        components (A) and optionally (B), (C) and/or (D),-   b) pelletizing the extrudate (E) obtained in step A) to obtain a    pelletized material (G) comprising components (A) and optionally    (B), (C) and/or (D),-   c) micronizing the pelletized material (G) obtained in step c) to    obtain the sinter powder (SP), preferably by grinding.

The present invention therefore also provides a method of producing asinter powder (SP), comprising the steps of

-   a) mixing components (A) and optionally (B), (C) and/or (D):    -   (A) at least one semicrystalline terephthalate polyester which        is prepared by reacting at least components (a) and (b):        -   (a) at least one aromatic dicarboxylic acid and        -   (b) at least two aliphatic diols (b1) and (b2), where the            aliphatic diol (b1) is neopentyl glycol,    -   (B) optionally at least one further polymer,    -   (C) optionally at least one additive and/or    -   (D) optionally at least one reinforcer,    -   in an extruder to obtain an extrudate (E) comprising        components (A) and optionally (B), (C) and/or (D),-   b) pelletizing the extrudate (E) obtained in step A) to obtain a    pelletized material (G) comprising components (A) and optionally    (B), (C) and/or (D),-   c) micronizing the pelletized material (G) obtained in step c) to    obtain the sinter powder (SP).

It will be apparent that, in the case that component (A) is already inpelletized form and the sinter powder (SP) of the invention comprisessolely component (A) and not components (B), (C) and (D), steps a) andb) may be dispensed with in the context of the present invention.

In a preferred embodiment, the sinter powder (SP) obtained in step c) isthen heat-treated in a step d) at a temperature T_(T) to obtain aheat-treated sinter powder (SP).

The method of producing a heat-treated sinter powder (SP) in that caseconsequently preferably comprises the following steps:

-   a) mixing components (A) and optionally (B), (C) and/or (D):    -   (A) at least one semicrystalline terephthalate polyester which        is prepared by reacting at least components (a) and (b):        -   (a) at least one aromatic dicarboxylic acid and        -   (b) at least two aliphatic diols (b1) and (b2), where the            aliphatic diol (b1) is neopentyl glycol,    -   (B) optionally at least one further polymer,    -   (C) optionally at least one additive and/or    -   (D) optionally at least one reinforcer,    -   in an extruder to obtain an extrudate (E) comprising        components (A) and optionally (B), (C) and/or (D),-   b) pelletizing the extrudate (E) obtained in step a) to obtain a    pelletized material (G) comprising components (A) and optionally    (B), (C) and/or (D),-   c) micronizing the pelletized material (G) obtained in step c) to    obtain the sinter powder (SP),-   d) heat-treating the sinter powder (SP) obtained in step c) at a    temperature T_(T) to obtain a heat-treated sinter powder (SP).

In a further preferred embodiment, the process for producing the sinterpowder (SP) comprises the following steps:

-   a) mixing components (A) and optionally (B), (C) and/or (D):    -   (A) at least one semicrystalline terephthalate polyester which        is prepared by reacting at least components (a) and (b):        -   (a) at least one aromatic dicarboxylic acid and        -   (b) at least two aliphatic diols (b1) and (b2), where the            aliphatic diol (b1) is neopentyl glycol,    -   (B) optionally at least one further polymer,    -   (C) optionally at least one additive and/or    -   (D) optionally at least one reinforcer,    -   in an extruder to obtain an extrudate (E) comprising        components (A) and optionally (B), (C) and/or (D),-   b) pelletizing the extrudate (E) obtained in step a) to obtain a    pelletized material (G) comprising components (A) and optionally    (B), (C) and/or (D),-   ci) micronizing the pelletized material (G) obtained in step c) to    obtain a terephthalate polyester powder (TP),-   cii) mixing the terephthalate polyester powder (TP) obtained in    step ci) with a flow aid to obtain the sinter powder (SP).

Preferably, the terephthalate polyester powder (TP) obtained in step ci)or the sinter powder (SP) obtained in step cii) is then heat-treated ina step d1) at a temperature T_(T) to obtain a heat-treated sinter powder(SP).

If the sinter powder (SP) comprises component (D), what is preferablyobtained is a pelletized material comprising solely components (A) andoptionally components (B) and/or (C) in premixed form. The at least onereinforcer (C) is then preferably mixed in only after the micronizationstep.

The method of producing the sinter powder (SP) in that case preferablycomprises the following steps:

-   a) mixing components (A) and optionally (B) and/or (C):    -   (A) at least one semicrystalline terephthalate polyester which        is prepared by reacting at least components (a) and (b):        -   (a) at least one aromatic dicarboxylic acid and        -   (b) at least two aliphatic diols (b1) and (b2), where the            aliphatic diol (b1) is neopentyl glycol,    -   (B) optionally at least one further polymer, and/or    -   (C) optionally at least one additive    -   in an extruder to obtain an extrudate (E) comprising        components (A) and optionally (B) and/or (C),-   b) pelletizing the extrudate (E) obtained in step A) to obtain a    pelletized material (G1) comprising components (A) and    optionally (B) and/or (C),-   c) micronizing the pelletized material (G1) obtained in step c) to    obtain a sinter powder (SP1), preferably by grinding,-   e) mixing the sinter powder (SP1) and component (D):    -   (D) at least one reinforcer,    -   to obtain the sinter powder (SP).

Preferably, the sinter powder (SP1) obtained in step c) or the sinterpowder (SP) obtained in step e) is then heat-treated in a step d2) at atemperature T_(T) to obtain a heat-treated sinter powder (SP),preference being given to heat-treating the sinter powder (SP1) obtainedin step c).

If, during the method of producing the sinter powder (SP), a flow aid ismixed in, the method then preferably comprises the following steps:

-   -   a) mixing components (A) and optionally (B) and/or (C):    -   (A) at least one semicrystalline terephthalate polyester which        is prepared by reacting at least components (a) and (b):        -   (a) at least one aromatic dicarboxylic acid and        -   (b) at least two aliphatic diols (b1) and (b2), where the            aliphatic diol (b1) is neopentyl glycol,    -   (B) optionally at least one further polymer, and/or    -   (C) optionally at least one additive    -   in an extruder to obtain an extrudate (E) comprising        components (A) and optionally (B) and/or (C),

-   b) pelletizing the extrudate (E) obtained in step a) to obtain a    pelletized material (G1) comprising components (A) and    optionally (B) and/or (C),

-   ci) micronizing the pelletized material (G1) obtained in step c) to    obtain a terephthalate polyester powder (TP1), preferably by    grinding,

-   cii) mixing the terephthalate polyester powder (TP1) obtained in    step ci) with a flow aid to obtain a sinter powder (SP2),

-   e) mixing the sinter powder (SP2) and component (D):    -   (D) at least one reinforcer,    -   to obtain the sinter powder (SP).

Preferably, the terephthalate polyester powder (TP1) obtained in stepci), the sinter powder (SP2) obtained in step cii) or the sinter powder(SP) obtained in step e) is then heat-treated in a step d3) at atemperature T_(T) to obtain a heat-treated sinter powder (SP).

Suitable flow aids are, for example, silicas, amorphous silicon oxide oraluminas. An example of a suitable alumina is Aeroxide® Alu C fromEvonik.

The present invention thus also provides a method of producing a sinterpowder (SP), in which the flow aid in step cii) is selected fromsilicas, amorphous silicon oxide and/or aluminas.

If the sinter powder (SP) comprises a flow aid, it is preferably addedin method step cii). In one embodiment, the sinter powder (SP) comprises0.02% to 1% by weight, preferably 0.05% to 0.8% by weight and morepreferably 0.1% to 0.6% by weight of flow aid, based in each case on thetotal weight of the terephthalate polyester powder (TP) or (TP1) and theflow aid.

In respect of the grinding in step c) and in step ci), the details andpreferences described above are correspondingly applicable with regardto the grinding.

Steps d), d1), d2) and d3) are preferably conducted at a temperatureT_(T) in the range from 80 to 140° C., more preferably in the range from85 to 135° C., and most preferably in the range from 100 to 130° C.

Steps d), d1), d2) and d3) are additionally preferably conducted withina period in the range from 1 to 20 hours. The heat treatment ispreferably effected in a drying cabinet under reduced pressure or underprotective gas. The protective gas used is, for example, nitrogen. Theheat treatment can be conducted in a static or moving vessel, such as atumble mixer.

The present invention therefore also further provides the sinter powder(SP) obtainable by the method of the invention.

Component (A)

According to the invention, component (A) is at least onesemicrystalline terephthalate polyester.

In the context of the present invention, “at least one semicrystallineterephthalate polyester (A)” means either exactly one semicrystallineterephthalate polyester (A) or a mixture of two or more semicrystallineterephthalate polyesters (A).

What is meant by “semicrystalline” in the context of the presentinvention is that the semicrystalline terephthalate polyester (A) has anenthalpy of fusion ΔH2_((A)) of greater than 1 J/g, preferably ofgreater than 2 J/g, measured in each case by means of differentialscanning calorimetry (DSC) to ISO 11357-4:2014.

The at least one semicrystalline terephthalate polyester (A) of theinvention thus typically has an enthalpy of fusion ΔH2_((A)) of greaterthan 1 J/g, preferably of greater than 2 J/g, measured in each case bymeans of differential scanning calorimetry (DSC) according to ISO11357-4:2014.

The at least one semicrystalline terephthalate polyester (A) of theinvention typically has an enthalpy of fusion ΔH2_((A)) of less than 150J/g, preferably of less than 100 J/g and especially preferably of lessthan 80 J/g, measured in each case by means of differential scanningcalorimetry (DSC) according to ISO 11357-4:2014.

Suitable semicrystalline terephthalate polyesters (A) generally have aviscosity number (VN(A)) in the range from 50 to 220 ml/g, preferably inthe range from 80 to 210 ml/g and especially preferably in the rangefrom 90 to 200 ml/g, determined in a 5 mg/ml by weight solution in aphenol/o-dichlorobenzene mixture (weight ratio 1:1 at 25° C.) to ISO1628.

Component (A) of the invention typically has a melting temperature(T_(M(A))). Preferably, the melting temperature (T_(M(A))) of component(A) is in the range from 130 to 210° C., more preferably in the rangefrom 135 to 205° C. and especially preferably in the range from 140 to180° C.

Suitable components (A) have a weight-average molecular weight(M_(W(A))) in the range from 500 to 2 000 000 g/mol, preferably in therange from 10 000 to 90 000 g/mol and especially preferably in the rangefrom 20 000 to 70 000 g/mol. Weight-average molecular weight (M_(W(A)))is determined by means of SEC-MALLS (Size ExclusionChromatography-Multi-Angle Laser Light Scattering) according to Chi-sanWu “Handbook of size exclusion chromatography and related techniques”,page 19.

The semicrystalline terephthalate polyester (A) can be prepared by allmethods known to those skilled in the art.

In the context of the present invention, the at least onesemicrystalline terephthalate polyester (A) is prepared by reacting atleast components (a) and (b):

-   (a) at least one aromatic dicarboxylic acid and-   (b) at least two aliphatic diols (b1) and (b2), where the aliphatic    diol (b1) is neopentyl glycol.

The conversion at least of components (a) and (b) is typically effectedin a condensation reaction. The term “condensation reaction” is known inprinciple to the person skilled in the art. In the context of thepresent invention, the term “condensation reaction” is understood tomean the reaction at least of components (a) and (b) with elimination ofwater and/or alcohol to obtain the semicrystalline terephthalatepolyester (A).

The molar ratio of component (a) to component (b) in the preparation ofthe at least one semicrystalline terephthalate polyester (A) ispreferably in the range from 1:0.8 to 1:1.1 [mol/mol], more preferablyin the range from 1:0.85 to 1:1.05 [mol/mol].

Component (a)

Component (a) is at least one aromatic dicarboxylic acid.

The expressions “at least one aromatic dicarboxylic acid” and “component(a)” in the context of the present invention are used synonymously andhave the same meaning. Furthermore, in the context of the presentinvention, the expression “at least one aromatic dicarboxylic acid” isunderstood to mean exactly one aromatic dicarboxylic acid, and mixturesof two or more aromatic dicarboxylic acids. In a preferred embodiment,in the method of the invention, exactly one aromatic dicarboxylic acidis used.

Aromatic dicarboxylic acids are known in principle to those skilled inthe art.

Aromatic dicarboxylic acids in the context of the present invention areunderstood to mean the aromatic dicarboxylic acids themselves and thederivatives of the aromatic dicarboxylic acids, such as aromaticdicarboxylic esters. Esters of the aromatic dicarboxylic acids includethe di-C₁-C₆-alkyl esters of the aromatic dicarboxylic acids, forexample the dimethyl, diethyl, di-n-propyl, diisopropyl, di-n-butyl,diisobutyl, di-t-butyl, di-n-pentyl, diisopentyl or di-n-hexyl esters ofthe aromatic dicarboxylic acids.

Examples of aromatic dicarboxylic acids are terephthalic acid,isophthalic acid, phthalic acid or the naphthalenedicarboxylic acids.

In the context of the present invention, the at least one aromaticdicarboxylic acid is preferably an aromatic dicarboxylic acids having 6to 12 and preferably one having 6 to 8 carbon atoms, more preferably onehaving 8 carbon atoms. The at least one aromatic dicarboxylic acid maybe linear or branched.

In a preferred embodiment of the present invention, the at least onearomatic dicarboxylic acid is selected from the group consisting ofterephthalic acid, isophthalic acid and phthalic acid.

It will be appreciated that it is also possible to use the esters of theabovementioned aromatic dicarboxylic acids as component (a). It ispossible here to use the esters of the abovementioned aromaticdicarboxylic acids individually or else as a mixture of two or moreesters of the aromatic dicarboxylic acids.

Furthermore, it is also possible to use a mixture of at least onearomatic dicarboxylic acid and at least one ester of an aromaticdicarboxylic acid.

Component (b)

Component (b) comprises at least two aliphatic diols (b1) and (b2),where the aliphatic diol (b1) is neopentyl glycol.

The expressions “at least two aliphatic diols (b1) and (b2), where thealiphatic diol (b1) is neopentyl glycol” and “component (b)” are usedsynonymously in the context of the present invention and have the samemeaning. Furthermore, in the context of the present invention, theexpression “at least two aliphatic diols (b1) and (b2)” is understood tomean exactly two aliphatic diols (b1) and (b2) and mixtures of threealiphatic diols (b1), (b2) and (b3) or more aliphatic diols (b1), (b2),(b3) and (bx). The expression “at least two aliphatic diols (b1) and(b2), where the aliphatic diol (b1) is neopentyl glycol” in the contextof the present invention is also understood to mean neopentyl glycol andexactly one further aliphatic diol (b2), and mixtures of neopentylglycol, the aliphatic diol (b2) and a further aliphatic diol (b3), orneopentyl glycol, the aliphatic diols (b2) and (b3) and more aliphaticdiols (bx).

In the context of the present invention, the aliphatic diol (b2) ispreferably different than the aliphatic diol (b1). The aliphatic diols(b3) and (bx) are preferably likewise different than the aliphatic diol(b1).

Aliphatic diols are known in principle to the person skilled in the art.

Examples of aliphatic diols are ethylene glycol, propane-1,3-diol,butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol, neopentyl glycol,2-ethyl-2-butylpropane-1,3-diol, 2-ethyl-2-isobutylpropane-1,3-diol,cyclohexane-1,4-dimethanol, 2,2,4-trimethylhexane-1,6-diol, polyethyleneglycol, diols of the dimer fatty acids or2,2,4,4-tetramethylcyclobutane-1,3-diol.

In the context of the present invention, the aliphatic diol (b1) isneopentyl glycol and the aliphatic diol (b2) is preferably

-   i) a linear diol of the general formula (I)

HO—(CH₂)_(n)—OH  (I)

-   -   in which n is 2, 3, 4, 5 or 6, more preferably 4, or

-   ii) a diol having a cycloalkyl radical, more preferably    cyclohexanedimethanol or 2,2,4,4-tetramethylcyclobutane-1,3-diol.

In the case that the at least one semicrystalline terephthalatepolyester (A) is prepared by the reaction of further aliphatic diols(b3) to (bx) with component (a), these are preferably selected fromlinear diols of the general formula (I) in which n is 2, 3, 4, 5 or 6,and/or from diols having a cycloalkyl radical.

The molar ratio of component (a) to component (b1) in the preparation ofthe at least one semicrystalline terephthalate polyester (A) is in therange from 1:0.15 to 1:0.65 [mol/mol], more preferably in the range from1:0.2 to 1:0.5 [mol/mol].

In a preferred embodiment, the at least one semicrystallineterephthalate polyester (A) is prepared by reacting at least components(a) and (b):

-   (a) terephthalic acid and-   (b) at least two aliphatic diols (b1) and (b2), where the aliphatic    diol (b1) is neopentyl glycol and the aliphatic diol (b2) is    -   i) a linear diol of the general formula (I)

HO—(CH₂)_(n)—OH  (I)

-   -   -   in which n is 2, 3, 4, 5 or 6, or

    -   ii) a diol having a cycloalkyl radical, more preferably        cyclohexanedimethanol or        2,2,4,4-tetramethylcyclobutane-1,3-diol.

In a particularly preferred embodiment, the at least one semicrystallineterephthalate polyester (A) is prepared by reacting at least components(a) and (b):

-   (a) terephthalic acid and-   (b) at least two aliphatic diols (b1) and (b2), where the aliphatic    diol (b1) is neopentyl glycol and the aliphatic diol (b2) is    butane-1,4-diol.

In this embodiment, the at least one semicrystalline terephthalatepolyester (A) is preferably prepared by reacting at least components (a)and (b):

-   (a) terephthalic acid and-   (b) at least two aliphatic diols (b1) and (b2), where the aliphatic    diol (b1) is neopentyl glycol and the aliphatic diol (b2) is    butane-1,4-diol,

where the molar ratio of component (a) to component (b) is in the rangefrom 1:0.8 to 1:1.1 [mol/mol] and the molar ratio of component (a) tocomponent (b1) is in the range from 1:0.1 to 1:0.75 [mol/mol].

In the condensation of components (a) and (b), it is additionallypossible to use at least one chain extender as an optional component(c).

The expressions “at least one chain extender” and “component (c)” in thecontext of the present invention are used synonymously and have the samemeaning. Furthermore, in the context of the present invention, theexpression “at least one chain extender” is understood to mean exactlyone chain extender, and mixtures of two or more chain extenders. In apreferred embodiment, exactly one chain extender is used.

The at least one chain extender is preferably selected from the groupconsisting of compounds comprising at least three groups capable ofester formation (c1) and from compounds comprising at least twoisocyanate groups (c2). Epoxides are likewise suitable chain extenders.

In the case that at least one chain extender is used as component (c),the at least one semicrystalline terephthalic polyester is prepared byreacting at least components (a), (b) and (c):

-   (a) at least one aromatic dicarboxylic acid,-   (b) at least two aliphatic diols (b1) and (b2), where the aliphatic    diol (b1) is neopentyl glycol, and-   c) at least one chain extender.

The sinter powder (SP) preferably comprises at least 15% by weight ofcomponent (A), more preferably at least 17% by weight of component (A),based on the sum total of the percentages by weight of components (A)and optionally (B), (C) and/or (D), preferably based on the total weightof the sinter powder (SP).

The sinter powder (SP) preferably further comprises up to 100% by weightof component (A), more preferably not more than 98.9% by weight,especially preferably not more than 95% by weight, most preferably notmore than 92% by weight of component (A), based on the sum total of thepercentages by weight of components (A) and optionally (B), (C) and/or(D), preferably based on the total weight of the sinter powder (SP).

Component (B)

Component (B) is at least one further polymer.

What is meant by “at least one further polymer” in the context of thepresent invention is either exactly one further polymer or a mixture oftwo or more further polymers.

The at least one further polymer (B) may be a semicrystalline oramorphous polymer.

If the at least one further polymer (B) is semicrystalline, it ispreferable in the context of the present invention that the at least onefurther semicrystalline polymer (B) is different than the at least onesemicrystalline terephthalate polyester of component (A).

Preferably, the at least one further polymer (B) is selected from thegroup consisting of polyolefins, polyesters, polyamides, polycarbonatesand polyacrylates, more preferably from polyesters, polycarbonates andpolyacrylates.

If the at least one further semicrystalline polymer (B) is selected frompolyesters, it is preferably a polycaprolactone.

If the sinter powder comprises component (B), it comprises at least 1%by weight of component (B), preferably at least 2% by weight ofcomponent (B), based on the sum total of the percentages by weight ofcomponents (A), (B) and optionally (C) and/or (D), preferably based onthe total weight of the sinter powder (SP).

If the sinter powder comprises component (B), moreover, it comprises notmore than 25% by weight of component (B), preferably not more than 23%by weight of component (B), based on the sum total of the percentages byweight of components (A), (B) and optionally (C) and/or (D), preferablybased on the total weight of the sinter powder (SP).

Component (C)

Component (C) is at least one additive.

In the context of the present invention, “at least one additive” meanseither exactly one additive or a mixture of two or more additives.

Additives as such are known to those skilled in the art. For example,the at least one additive is selected from the group consisting ofantinucleating agents, impact modifiers, flame retardants, stabilizers,conductive additives, end group functionalizers, dyes, antioxidants(preferably from sterically hindered phenols) and color pigments.

An example of a suitable antinucleating agent is lithium chloride.Suitable impact modifiers are, for example, ethylene-propylene-dienerubbers, or those based on terpolymers of ethylene, methyl acrylate andglycidyl methacrylate (GMA). Suitable flame retardants are, for example,phosphinic salts. Suitable stabilizers are, for example, phenols,phosphites, for example sodium hypophosphite, and copper stabilizers.Suitable conductive additives are carbon fibers, metals, stainless steelfibers, carbon nanotubes and carbon black. Suitable end groupfunctionalizers are, for example, terephthalic acid, adipic acid andpropionic acid. Suitable dyes and color pigments are, for example,carbon black and iron chromium oxides.

An example of a suitable antioxidant is Irganox® 245 from BASF SE orLotader® AX8900 from Arkema.

If the sinter powder comprises component (C), it comprises at least 0.1%by weight of component (C), preferably at least 1% by weight ofcomponent (C), based on the sum total of the percentages by weight ofcomponents (A), (C) and optionally (B) and/or (D), preferably based onthe total weight of the sinter powder (SP).

If the sinter powder comprises component (C), moreover, it comprises notmore than 20% by weight of component (C), based on the sum total of thepercentages by weight of components (A), (C) and optionally (B) and/or(D), preferably based on the total weight of the sinter powder (SP).

Component (D)

According to the invention, any component (D) present is at least onereinforcer.

In the context of the present invention, “at least one reinforcer” meanseither exactly one reinforcer or a mixture of two or more reinforcers.

In the context of the present invention, a reinforcer is understood tomean a material that improves the mechanical properties of shaped bodiesproduced by the process of the invention compared to shaped bodies thatdo not comprise the reinforcer.

Reinforcers as such are known to those skilled in the art. Component (D)may, for example, be in spherical form, in platelet form or in fibrousform.

Preferably, the at least one reinforcer is in platelet form or infibrous form.

A “fibrous reinforcer” is understood to mean a reinforcer in which theratio of length of the fibrous reinforcer to the diameter of the fibrousreinforcer is in the range from 2:1 to 40:1, preferably in the rangefrom 3:1 to 30:1 and especially preferably in the range from 5:1 to20:1, where the length of the fibrous reinforcer and the diameter of thefibrous reinforcer are determined by microscopy by means of imageevaluation on samples after ashing, with evaluation of at least 70 000parts of the fibrous reinforcer after ashing.

The length of the fibrous reinforcer in that case is typically in therange from 5 to 1000 μm, preferably in the range from 10 to 600 μm andespecially preferably in the range from 20 to 200 μm, determined bymeans of microscopy with image evaluation after ashing.

The diameter in that case is, for example, in the range from 1 to 30 μm,preferably in the range from 2 to 20 μm and especially preferably in therange from 5 to 15 μm, determined by means of microscopy with imageevaluation after ashing.

In a further preferred embodiment, the at least one reinforcer is inplatelet form. In the context of the present invention, “in plateletform” is understood to mean that the particles of the at least onereinforcer have a ratio of diameter to thickness in the range from 4:1to 10:1, determined by means of microscopy with image evaluation afterashing.

Suitable reinforcers are known to those skilled in the art and areselected, for example, from the group consisting of carbon nanotubes,carbon fibers, boron fibers, glass fibers, glass beads, silica fibers,ceramic fibers, basalt fibers, aluminosilicates, aramid fibers andpolyester fibers.

The at least one reinforcer is preferably selected from the groupconsisting of aluminosilicates, glass fibers, glass beads, silica fibersand carbon fibers.

The at least one reinforcer is more preferably selected from the groupconsisting of aluminosilicates, glass fibers, glass beads and carbonfibers. These reinforcers may additionally have beenepoxy-functionalized.

Suitable silica fibers are, for example, wollastonite and halloysite.

Suitable aluminosilicates are known as such to the person skilled in theart. Aluminosilicates refer to compounds comprising Al₂O₃ and SiO₂. Instructural terms, a common factor among the aluminosilicates is that thesilicon atoms are tetrahedrally coordinated by oxygen atoms and thealuminum atoms are octahedrally coordinated by oxygen atoms.Aluminosilicates may additionally comprise further elements.

Preferred aluminosilicates are sheet silicates. Particularly preferredaluminosilicates are calcined aluminosilicates, especially preferablycalcined sheet silicates. The aluminosilicate may additionally have beenepoxy-functionalized.

If the at least one reinforcer is an aluminosilicate, thealuminosilicate may be used in any form. For example, it can be used inthe form of pure aluminosilicate, but it is likewise possible that thealuminosilicate is used in mineral form. Preferably, the aluminosilicateis used in mineral form. Suitable aluminosilicates are, for example,feldspars, zeolites, sodalite, sillimanite, andalusite and kaolin.Kaolin is a preferred aluminosilicate.

Kaolin is one of the clay rocks and comprises essentially the mineralkaolinite. The empirical formula of kaolinite is Al₂[(OH)₄/Si₂O₅].Kaolinite is a sheet silicate. As well as kaolinite, kaolin typicallyalso comprises further compounds, for example titanium dioxide, sodiumoxides and iron oxides. Kaolin preferred in accordance with theinvention comprises at least 98% by weight of kaolinite, based on thetotal weight of the kaolin.

If the sinter powder comprises component (D), it comprises at least 5%by weight of component (D), more preferably at least 10% by weight ofcomponent (D), based on the sum total of the percentages by weight ofcomponents (A), (D) and optionally (B) and/or (C), preferably based onthe total weight of the sinter powder (SP).

If the sinter powder comprises component (D), moreover, it preferablycomprises not more than 40% by weight of component (D), based on the sumtotal of the percentages by weight of components (A), (D) and optionally(B) and/or (C), preferably based on the total weight of the sinterpowder (SP).

Method of Producing the Shaped Bodies

The present invention further provides a method of producing a shapedbody, comprising the steps of:

-   a) providing a layer of the sinter powder (SP),-   b) optionally heating the layer up to a maximum of 2 K below the    melting temperature T_(M) of the sinter powder (SP),-   c) exposing the layer of the sinter powder (SP) provided in step a)    or optionally heated in step b), preferably in a sintering method,    more preferably in a selective laser sintering method, in a    high-speed sintering (HSS) method or a multijet fusion (MJF) method.

In step c), the layer of the sinter powder (SP) provided in step a), oroptionally step b), is exposed.

On exposure, at least some of the layer of the sinter powder (SP) melts.The molten sinter powder (SP) coalesces and forms a homogeneous melt.After the exposure, the molten part of the layer of the sinter powder(SP) cools down again and the homogeneous melt solidifies again.

Suitable methods of exposure include all methods known to those skilledin the art. Preferably, the exposure in step c) is effected with aradiation source. The radiation source is preferably selected from thegroup consisting of infrared sources and lasers. Especially preferredinfrared sources are near infrared sources.

The present invention therefore also provides a method in which theexposing in step c) is effected with a radiation source selected fromthe group consisting of lasers and infrared sources.

Suitable lasers are known to those skilled in the art and are forexample semiconductor fiber lasers, solid-state lasers, for exampleNd:YAG lasers (neodymium-doped yttrium aluminum garnet lasers), orcarbon dioxide lasers. The carbon dioxide laser typically has awavelength of 10.6 μm. Other usable lasers emit radiation in the rangefrom 350 to 2500 nm.

If the radiation source used in the exposing in step c) is a laser, thelayer of the sinter powder (SP) provided in step a), or optionally stepb), is typically exposed locally and briefly to the laser beam. Thisselectively melts just the parts of the sinter powder (SP) that havebeen exposed to the laser beam. If a laser is used in step c), themethod of the invention is also referred to as selective lasersintering. Selective laser sintering is known per se to those skilled inthe art.

If the radiation source used in the exposing in step c) is an infraredsource, especially a near infrared source, the wavelength at which theradiation source radiates is typically in the range from 680 nm to 3000nm, preferably in the range from 750 nm to 1500 nm and especially in therange from 880 nm to 1100 nm.

In the exposing in step c), in that case, the entire layer of the sinterpowder (SP) is typically exposed. In order that only the desired regionsof the sinter powder (SP) melt in the exposing, an infrared-absorbingink (IR-absorbing ink) is typically applied to the regions that are tomelt.

The method of producing the shaped body in that case preferablycomprises, between step a) and optionally between step b) or step c), astep a-1) of applying at least one IR-absorbing ink to at least part ofthe layer of the sinter powder (SP) provided in step a).

The present invention therefore also further provides a method ofproducing a shaped body, comprising the steps of

-   a) providing a layer of a sinter powder (SP) comprising the    following components (A) and optionally (B), (C) and/or (D):    -   (A) at least one semicrystalline terephthalate polyester which        is prepared by reacting at least components (a) and (b):        -   (a) at least one aromatic dicarboxylic acid and        -   (b) at least two aliphatic diols (b1) and (b2), where the            aliphatic diol (b1) is neopentyl glycol,    -   (B) optionally at least one further polymer    -   (C) optionally at least one additive and/or    -   (D) optionally at least one reinforcer,-   a-1) applying at least one IR-absorbing ink to at least part of the    layer of the sinter powder (SP) provided in step a),-   b) optionally heating the layer up to a maximum of 2 K below the    melting temperature T_(M) of the sinter powder (SP),-   c) exposing the layer of the sinter powder (SP) provided in step a)    or optionally heated in step b).

Suitable IR-absorbing inks are all IR-absorbing inks known to thoseskilled in the art, especially IR-absorbing inks known to those skilledin the art for high-speed sintering.

IR-absorbing inks typically comprise at least one absorber that absorbsIR radiation, preferably NIR radiation (near infrared radiation). In theexposing of the layer of the sinter powder (SP) in step c), theabsorption of the IR radiation, preferably the NIR radiation, by the IRabsorber present in the IR-absorbing inks results in selective heatingof the part of the layer of the sinter powder (SP) to which theIR-absorbing ink has been applied.

The IR-absorbing ink may, as well as the at least one absorber, comprisea carrier liquid. Suitable carrier liquids are known to those skilled inthe art and are, for example, oils or solvents.

The at least one absorber may be dissolved or dispersed in the carrierliquid.

If the exposure in step c) is effected with a radiation source selectedfrom infrared sources and if step a-1) is conducted, the method of theinvention is also referred to as high-speed sintering (HSS) or multijetfusion (MJF) method. These methods are known per se to those skilled inthe art.

After step c), the layer of the sinter powder (SP) is typically loweredby the layer thickness of the layer of the sinter powder (SP) providedin step a) and a further layer of the sinter powder (SP) is applied.This is subsequently optionally heated again in step b) and exposedagain in step c).

This firstly bonds the upper layer of the sinter powder (SP) to thelower layer of the sinter powder (SP); in addition, the particles of thesinter powder (SP) within the upper layer are bonded to one another byfusion.

In the process of the invention, steps a) to c) and optionally a-1) canthus be repeated.

By repeating the lowering of the powder bed, the applying of the sinterpowder (SP) and the exposure and hence the melting of the sinter powder(SP), three-dimensional shaped bodies are produced. It is possible toproduce shaped bodies that also have cavities, for example. Noadditional support material is necessary since the unmolten sinterpowder (SP) itself acts as a support material.

The present invention therefore also further provides a shaped bodyobtainable by the method of the invention.

Of particular significance in the method of the invention is the meltingrange of the sinter powder (SP), called the sintering window (W_(SP)) ofthe sinter powder (SP).

The sintering window (W_(SP)) of the sinter powder (SP) can bedetermined by differential scanning calorimetry (DSC) for example.

In differential scanning calorimetry, the temperature of a sample, i.e.in the present case a sample of the sinter powder (SP), and thetemperature of a reference are altered linearly over time. To this end,heat is supplied to/removed from the sample and the reference. Theamount of heat Q necessary to keep the sample at the same temperature asthe reference is determined. The amount of heat QR supplied to/removedfrom the reference serves as a reference value.

If the sample undergoes an endothermic phase transformation, anadditional amount of heat Q must be supplied to keep the sample at thesame temperature as the reference. If an exothermic phase transformationtakes place, an amount of heat Q has to be removed to keep the sample atthe same temperature as the reference. The measurement affords a DSCdiagram in which the amount of heat Q supplied to/removed from thesample is plotted as a function of temperature T.

Measurement typically involves initially performing a heating run (H),i.e. the sample and the reference are heated in a linear manner. Duringthe melting of the sample (solid/liquid phase transformation), anadditional amount of heat Q has to be supplied to keep the sample at thesame temperature as the reference. In the DSC diagram, a peak known asthe melting peak is then observed.

After the heating run (H), a cooling run (C) is typically measured. Thisinvolves cooling the sample and the reference linearly, i.e. heat isremoved from the sample and the reference. During thecrystallization/solidification of the sample (liquid/solid phasetransformation), a greater amount of heat Q has to be removed to keepthe sample at the same temperature as the reference, since heat isliberated in the course of crystallization/solidification. In the DSCdiagram of the cooling run (C), a peak, called the crystallization peak,is then observed in the opposite direction from the melting peak.

In the context of the present invention, the heating during the heatingrun is typically effected at a heating rate in the range from 5 to 25K/min, preferably at a heating rate in the range from 5 to 15 K/min. Thecooling during the cooling run, in the context of the present invention,is typically effected at a cooling rate in the range from 5 to 25 K/min,preferably at a cooling rate in the range from 5 to 15 K/min.

A DSC diagram with a heating run (H) and a cooling run (K) with aheating rate/cooling rate in the range from 5 to 15 K is shown by way ofexample in FIG. 1 . The DSC diagram can be used to determine the onsettemperature of melting (T_(M) ^(onset)) and the onset temperature ofcrystallization (T_(C) ^(onset)).

To determine the onset temperature of melting (T_(M) ^(onset)), atangent is drawn against the baseline of the heating run (H) at thetemperatures below the melting peak. A second tangent is drawn againstthe first point of inflection of the melting peak at temperatures belowthe temperature at the maximum of the melting peak. The two tangents areextrapolated until they intersect. The vertical extrapolation of theintersection to the temperature axis denotes the onset temperature ofmelting (T_(M) ^(onset)).

To determine the onset temperature of crystallization (Tense), a tangentis drawn against the baseline of the cooling run (C) at the temperaturesabove the crystallization peak. A second tangent is drawn against thepoint of inflection of the crystallization peak at temperatures abovethe temperature at the minimum of the crystallization peak. The twotangents are extrapolated until they intersect. The verticalextrapolation of the intersection to the temperature axis indicates theonset temperature of crystallization (T_(C) ^(onset)).

The sintering window (W) results from the difference between the onsettemperature of melting (T_(M) ^(onset)) and the onset temperature ofcrystallization (T_(C) ^(onset)). Thus:

W=T _(M) ^(onset) −T _(C) ^(onset).

In the context of the present invention, the terms “sintering window(W_(SP))”, “size of the sintering window (WSP)” and “difference betweenthe onset temperature of melting (T_(M) ^(onset)) and the onsettemperature of crystallization (T_(C) ^(onset))” have the same meaningand are used synonymously.

The sinter powder (SP) of the invention is of particularly goodsuitability for use in a sintering method.

The present invention therefore also provides for the use of a sinterpowder (SP) comprising the following components (A) and optionally (B),(C) and/or (D):

-   (A) at least one semicrystalline terephthalate polyester which is    prepared by reacting at least components (a) and (b):    -   (a) at least one aromatic dicarboxylic acid and    -   (b) at least two aliphatic diols (b1) and (b2), where the        aliphatic diol (b1) is neopentyl glycol,-   (B) at least one further polymer,-   (C) optionally at least one additive and/or-   (D) optionally at least one reinforcer, in a sintering method,    preferably in a selective laser sintering method, in a high-speed    sintering method (HSS) or a multijet fusion method (MJF).

Shaped Bodies

The method of the invention affords a shaped body. The shaped body canbe removed from the powder bed directly after the solidification of thesinter powder (SP) molten on exposure in step c). It is likewisepossible first to cool the shaped body and only then to remove it fromthe powder bed. Any adhering particles of the sinter powder that havenot been melted can be mechanically removed from the surface by knownmethods. Methods for surface treatment of the shaped body include, forexample, vibratory grinding or barrel polishing, and also sandblasting,glass bead blasting or microbead blasting.

It is also possible to subject the shaped bodies obtained to furtherprocessing or, for example, to treat the surface.

The present invention therefore further provides a shaped bodyobtainable by the method of the invention.

The shaped bodies obtained typically comprise in the range from 15% to100% by weight of component (A), in the range from 0% to 25% by weightof component (B), in the range from 0% to 20% by weight of component (C)and in the range from 0% to 40% by weight of component (D), based ineach case on the total weight of the shaped body.

In a preferred embodiment, the shaped body comprises in the range from15% to 95% by weight of component (A), in the range from 0% to 25% byweight of component (B), in the range from 0% to 20% by weight ofcomponent (C) and in the range from 5% to 40% by weight of component(D), based in each case on the total weight of the shaped body.

In an alternative preferred embodiment, the -shaped body comprises

in the range from 15% to 98.9% by weight, preferably in the range from17% to 92% by weight, of component (A),

in the range from 1% to 25% by weight, preferably in the range from 2%to 23% by weight, of component (B),

in the range from 0.1% to 20% by weight, preferably in the range from 1%to 20% by weight, of component (C) and

in the range from 0% to 40% by weight, preferably in the range from 5%to 40% by weight, of component (D),

based in each case on the total weight of the shaped body.

In general, component (A) is the component (A) that was present in thesinter powder (SP). It is likewise the case that component (B) is thecomponent (B) that was present in the sinter powder (SP), the component(C) is the component (C) that was present in the sinter powder (SP), andthe component (D) is the component (D) that was present in the sinterpowder (SP).

If step a-1) has been conducted, the shaped body additionally typicallycomprises the IR-absorbing ink.

It will be clear to the person skilled in the art that, as a result ofthe exposure of the sinter powder (SP), components (A) and optionally(B), (C) and (D) can enter into chemical reactions and can be altered asa result. Such reactions are known to those skilled in the art.

Preferably, components (A) and optionally (B), (C) and (D) do not enterinto any chemical reaction on exposure in step c); instead, the sinterpowder (SP) merely melts.

The resultant shaped body preferably has a tensile modulus ofelasticity, determined to ISO 527-1:2012, of at least 1000 MPa, morepreferably of at least 1400 MPa, and especially preferably of at least1800 MPa.

In addition, the resultant shaped body preferably has a tensilestrength, determined to ISO 527-1:2012, of at least 15 MPa, morepreferably of at least 20 MPa, and especially preferably of at least 25MPa.

In a further embodiment of the present invention, the sinter powder (SP)comprises the following components (A) and optionally (B), (C) and/or(D):

(A) at least one semicrystalline terephthalate polyester which isprepared by reacting at least components (a) and (b):(a) at least one aromatic dicarboxylic acid and(b) at least two aliphatic diols (b1) and (b2), where the aliphatic diol(b1) is neopentyl glycol,(B) optionally at least one further polymer,(C) optionally at least one additive and/or(D) optionally at least one reinforcer.

Preferably, the molar ratio of component (a) to component (b1) in thepreparation of the at least one semicrystalline terephthalate polyester(A) is in the range from 1:0.1 to 1:0.75 [mol/mol]. The embodiments andpreferences specified above relating to the sinter powder (SP) accordingto claim 1 are analogously applicable here.

The invention is elucidated in detail hereinafter by examples, withoutrestricting it thereto.

EXAMPLES

The following components are used:

Semicrystalline Terephthalate Polyester

-   -   Component (A) in inventive examples E1, E2, E4, E5, E6 and E7    -   Advanite 53001 terephthalate polyester (pelletized material;        Sasa Polyester Sanayi A.S., Turkey), prepared by reaction of        components (a), (b1) and (b2):    -   52.4 mol % of terephthalic acid (component (a)), based on the        total amount of components (a), (b1) and (b2),    -   12.2 mol % of neopentyl glycol (component (b1)), based on the        total amount of components (a), (b1) and (b2), and    -   35.4 mol % of butanediol (component (b2)), based on the total        amount of components (a), (b1) and (b2).

Semicrystalline Terephthalate Polyester in Comparative Example CE3

-   -   Ultradur B4500 polybutylene terephthalate (pelletized material;        BASF SE), prepared by reaction of components (a) and (b2):    -   50 mol % of terephthalic acid or dimethyl terephthalate        (corresponding to component (a)), based on the total amount of        components (a) and (b2), and    -   50 mol % of butane-1,4-diol (corresponding to component (b2)),        based on the total amount of components (a) and (b2).

Further Polymer (Component (8)) in Inventive Examples E6 and E7

-   -   Capa® 6500 polycaprolactone (pelletized material; Perstorp)

Additive (Component (C)) in Inventive Examples E6 and E7

-   -   Irganox® 245 antioxidant (BASF SE; sterically hindered phenol)

Reinforcer (Component (D)) in Inventive Examples E4 and E5

-   -   glass beads (Spheriglass® 2000 CP0202; Potters; B4)    -   wollastonite (TREMIN® 939-300 EST; HPF; B5)

Flow Aid

-   -   Aeroxide® Alu C (Evonik)

Test Methods:

The enthalpies of fusion ΔH1 and ΔH2, melting temperature (T_(M1)) andglass transition temperature (T_(G2)) were each determined by means ofdynamic scanning calorimetry.

For determination of the melting temperature (T_(M1)) and the firstenthalpy of fusion ΔH1, as described above, a first heating run (H1) ata heating rate of 20 K/min was measured. For determination of the secondenthalpy of fusion ΔH2, as described above, a second heating run (H2) ata heating rate of 20 K/min was measured. The melting temperature(T_(M1)) then corresponded to the temperature at the maximum of themelting peak of the heating run (H1). The enthalpies of fusionΔH1_((SP)) and ΔH2_((SP)) of the sinter powder (SP) are proportional tothe area beneath the melting peak of the first heating (H1) and of thesecond heating run (H2) respectively in the DSC diagram.

For determination of the glass transition temperature (T_(G2)), afterthe first heating run (H1), a cooling run (K) and subsequently a secondheating run (H2) were measured. The cooling run was measured at acooling rate of 20 K/min; the first heating run (H1) and the secondheating run (H2) were measured at a heating rate of 20 K/min. The glasstransition temperature (T_(G2)) was then determined as described aboveat half the step height of the second heating run (H2).

The crystallization temperature (T_(C)) was determined by means ofdifferential scanning calorimetry. For this purpose, first a heating run(H) at a heating rate of 20 K/min and then a cooling run (C) at acooling rate of 20 K/min were measured. The crystallization temperature(T_(C)) is the temperature at the extreme of the crystallization peak.

Complex shear viscosity was determined using freshly produced sinterpowders. Viscosity was measured here by means of rotary rheology at ameasurement frequency of 0.5 rad/s at a temperature of 190° C. (E1, E2,E6 and E7) or 240° C. (CE3).

Production of the Sinter Powders

Inventive Examples E1, E2, E4 and E5 and Comparative Example CE3

The pelletized materials of the semicrystalline terephthalate polyesterswere each ground while cooling with liquid nitrogen in a pinned diskmill to a particle size (D50) in the region of less than 150 μm toobtain a terephthalate polyester powder. The resultant terephthalatepolyester powder was mixed with 0.2% by weight of flow aid, based on thetotal weight of the terephthalate polyester powder and the flow aid, or,based on the total weight of the sinter powder, to obtain the sinterpowder (SP).

In inventive example E2, the resultant sinter powder (SP) wassubsequently subjected to heat treatment at a temperature of 120° C. for20 hours in a drying cabinet under reduced pressure to obtain aheat-treated sinter powder (SP). In inventive example E1, the sinterpowder (SP) was not heat-treated. In inventive examples E4 and E5, afterthe sinter powder had been heat treated, a reinforcer (component (D)),glass beads (E4) and wollastonite (E5) were mixed in. The compositionsof the sinter powders (SP) and of the heat-treated sinter powders (SP)are shown in tables 1 and 2; the physical properties of the sinterpowders (SP) and of the heat-treated sinter powders (SP) are shown intables 4 and 5.

Inventive Examples E6 and E7

The pellets of the semicrystalline terephthalate polyester (component(A)) and of the further polymer (component (B); polycaprolactone) andthe antioxidant (component (C)) in the amounts specified in table 3 weremixed in an extruder to obtain an extrudate (E) and then pelletized toobtain a pelletized material (G). Subsequently, the pelletized material(G) was ground while cooling with liquid nitrogen in a pinned disk millto a particle size (D50) in the region of less than 150 μm to obtain thesinter powder (SP). In inventive examples E6 and E7, the sinter powder(SP) was not heat-treated. The physical properties of the sinter powders(SP) are shown in tables 4 and 5.

TABLE 1 Example/ Terephthalate Component Component Component Comparativepolyester powder (a) (b1) (b2) Flow aid example [% by wt]* [mol %]**[mol %]** [mol %]** [% by wt.]* E1 99.8 52.4 12.2 35.4 0.2 E2 99.8 52.412.2 35.4 0.2 CE3 99.8 50 — 50 0.2 *based on the tota weight of thesinter powder **based on the tota amount c of components (a), (b1) and(b2)

TABLE 2 Terephthalate Example/ polyester Component Component Componentcomparative powder (a) (b1) (b2) Flow aid Reinforcer example  

  [mol %]** [mol %]** [% by wt.]* [% by wt.]* [% by wt.]* E4 82.83 52.412.2 35.4 0.17 17 E5 82.83 52.4 12.2 35.4 0.17 17 *based on the totaweight of the sinter powder **based on the total amount of components(a), (b1) and (b2)

indicates data missing or illegible when filed

TABLE 3 Component Component Example/ Component Component ComponentComponent (B) (C) comparative (A) (a) (b1) (b2) [% by [% by example [%by wt.]* [mol %]** [mol %]** [mol %]** wt 

 ]* wt 

 ]* E6 97.25 52.4 12.2 35.4 2.5 0.25 E7 94.75 52.4 12.2 35.4 5.0 0.25*based on the total weight of the sinter powder **based on the totalamount of components (a), (b1) and (b2)

indicates data missing or illegible when filed

TABLE 4 Example/ comparative D10 D50 D90 example [μm] [μm] [μm] E1 37 62101 E2 37 62 101 CE3 30.7 61.5 115.6 E6 E7

TABLE 5 Complex shear Example/ viscosity comparative at 0.5 rad/ T_(M1)T_(G2) T_(C) ΔH₁ ΔH₂ ΔH₁ − ΔH₂ example s [Pas] [° C.] [° C.] [° C.][J/g] [J/g] [J/g] E1 1500 83.1 43.0 100.1 30 2 28 167.1 E2 1540 167.544.0 101.0 38 3 35 CE3 580 221.9 42.0 190.8 53 59 6 E4 — 167.1 44.0103.0 31 4 27 E5 — 168.4 44.0 114.0 29 10 19 E6 315 168.0 42.0 100.6 3217 15 E7 320 167.4 38.0 98.6 26 12 14

The sinter powders of inventive examples E1, E2, E3, E4, E5, E6 and E7show a distinctly lower melting temperature (T_(M1)) than the sinterpowder of comparative example CE3, as a result of which the sinterpowders of inventive examples E1, E2, E3, E4, E5, E6 and E7 can be usedwithout difficulty in all standard laser sintering systems with maximumbuild space temperatures of 200° C. The sinter powders of inventiveexamples E1, E2, E3, E4, E5, E6 and E7 likewise feature very slowcrystallization compared to the sinter powder of comparative exampleCE3, which shows the difference in the enthalpies of fusion from thefirst and second heating runs, and which achieves a distinctly broadenedsintering window.

On comparison of examples E1 and E2, it is clear that an additional,low-lying fusion peak (83.1° C.) occurs in the case of E1. The effect ofthis is tackiness in the SLS process, which makes sinter powder E1 moredifficult to process (see table 7). Heat treatment (example E2) leads todisappearance of this low-lying melting peak in the first heating runand to improved processibility.

This peak does not occur in inventive examples E6 and E7.

Laser Sintering Experiments

The sinter powder was introduced with a layer thickness of 0.1 mm intothe cavity at the temperature specified in table 6. The sinter powderwas subsequently exposed to a laser with the laser power outputspecified in table 6 and the point spacing specified, with a speed ofthe laser over the sample during exposure of 15 m/s. The point spacingis also known as laser spacing or lane spacing. Selective lasersintering typically involves scanning in stripes. The point spacinggives the distance between the centers of the stripes, i.e. between thetwo centers of the laser beam for two stripes.

TABLE 6 Example/ Laser power Laser Point comparative Temperature outputspeed spacing example [° C.] [W] [m/s] [mm] E1 140 50 15 0.18 E2 135-15550 15 0.18 CE3 205-215 50 15 0.18 E4 140 50 15 0.18 E5 140 50 15 0.18

It is clear that the temperature with which the sinter powder ofinventive examples E1 and E2 enters the build space, at 25° C. below themelting temperature, is very low compared to the temperature at whichthe sinter powder of comparative example CE3 was introduced into thebuild space.

Subsequently, the properties of the tensile bars (sinter bars) obtainedwere determined. The tensile bars (sinter bars) obtained were tested inthe dry state after drying at 80° C. for 336 h under reduced pressure.The results are shown in table 7. In addition, Charpy specimens wereproduced, which were likewise tested in dry form (according toISO179-2/1eU: 1997+Amd.1:2011).

Processibility was assessed qualitatively with “2” meaning “good”, i.e.low warpage of the component, and “5” meaning “inadequate”, i.e. severewarpage of the component.

Tensile strength, tensile modulus of elasticity and elongation at breakwere determined according to ISO 527-1:2012.

TABLE 7 Charpy impact Example/ Tensile resistance, Charpy impactcomparative Processibility Tensile modulus of Elongation at unnotchedresistance, example in SLS strength [MPa] elasticity [MPa] break [%][kJ/m²] notched [kJ/m²] E1 3 45 2300 2.5 n.d. n.d. E2 1 37-45 2300-24301.7-2.5 9-12 2.2 ± 0.2 CE3 6 n.d* n.d* n.d* n.d* n.d* E4 1 42 ± 1.3 2850± 45 1.7 ± 0.1  7.4 ± 0.6 1.6 ± 0.3 E5 1 45 ± 0.7 3740 ± 85 1.7 ± 0.113.1 ± 1.5 1.7 ± 0.2 *No mechanically testable components were obtainedsince warpage was too great

The shaped bodies produced from the inventive sinter powders accordingto examples E1, E2, E4 and E5 have reduced warpage together with a hightensile modulus of elasticity and high tensile strength. The mixing of areinforcer (component (D)) into the sinter powder (SP) (E4 and E5) canachieve a further increase in tensile modulus of elasticity and tensilestrength.

1.-14. (canceled)
 15. A sinter powder (SP) comprising the followingcomponents (A) and optionally (B), (C) and/or (D): (A) at least onesemicrystalline terephthalate polyester which is prepared by reacting atleast components (a) and (b): (a) at least one aromatic dicarboxylicacid and (b) at least two aliphatic diols (b1) and (b2), where thealiphatic diol (b1) is neopentyl glycol, (B) optionally at least onefurther polymer, (C) optionally at least one additive and/or (D)optionally at least one reinforcer, where the molar ratio of component(a) to component (b1) in the preparation of the at least onesemicrystalline terephthalate polyester (A) is in the range from 1:0.15to 1:0.65 [mol/mol] and the aliphatic diol (b2) is a linear diol of thegeneral formula (I)HO—(CH₂)_(n)—OH  (I) in which n is 2, 3, 4, 5 or
 6. 16. The sinterpowder (SP) according to claim 15, wherein the molar ratio of component(a) to component (b) in the preparation of the at least onesemicrystalline terephthalate polyester (A) is in the range from 1:0.8to 1:1.1 [mol/mol].
 17. The sinter powder (SP) according to claim 15,wherein the molar ratio of component (a) to component (b1) in thepreparation of the at least one semicrystalline terephthalate polyester(A) is in the range from 1:0.2 to 1:0.5 [mol/mol].
 18. The sinter powder(SP) according to claim 15, wherein component (a) is selected from thegroup consisting of terephthalic acid, isophthalic acid and phthalicacid.
 19. The sinter powder (SP) according to claim 15, wherein thesinter powder (SP) has i. a median particle size (D50) in the range from10 to 250 μm, and/or ii. a D10 in the range from 10 to 60 μm, a D50 inthe range from 25 to 90 μm and a D90 in the range from 50 to 150 μm,and/or iii. has been heat treated.
 20. The sinter powder (SP) accordingto claim 15, wherein i) component (B) is a polymer selected from thegroup consisting of polyolefins, polyesters, polyamides, polycarbonatesand polyacrylates, and/or ii) component (C) is selected fromantinucleating agents, impact modifiers, flame retardants, stabilizers,conductive additives, end group functionalizers, dyes, antioxidants andcolor pigments, and/or iii) component (D) is selected from the groupconsisting of carbon nanotubes, carbon fibers, boron fibers, glassfibers, glass beads, silica fibers, ceramic fibers, basalt fibers,aluminum silicates, aramid fibers and polyester fibers.
 21. The sinterpowder (SP) according to claim 15, wherein the sinter powder (SP) has amelting temperature (T_(M)) in the range from 130 to 210° C., where themelting temperature (T_(M)) is determined by dynamic scanningcalorimetry according to the description.
 22. The sinter powder (SP)according to claim 15, wherein the sinter powder (SP) has acrystallization temperature (T_(C)) in the range from 70 to 130° C.,where the crystallization temperature (T_(M)) is determined by dynamicscanning calorimetry according to the description.
 23. The sinter powderaccording to claim 15, wherein the sinter powder (SP) has a firstenthalpy of fusion ΔH1_((SP)) and a second enthalpy of fusionΔH2_((SP)), where the difference between the first enthalpy of fusionΔH1_((SP)) and the second enthalpy of fusion ΔH2_((SP)) is at least 10J/g, where the first enthalpy of fusion ΔH1_((SP)) and the secondenthalpy of fusion ΔH2_((SP)) are determined by dynamic scanningcalorimetry according to the description.
 24. A method of producing asinter powder (SP) according to claim 15, comprising the steps of a)mixing components (A) and optionally (B), (C) and/or (D): (A) at leastone semicrystalline terephthalate polyester which is prepared byreacting at least components (a) and (b): (a) at least one aromaticdicarboxylic acid and (b) at least two aliphatic diols (b1) and (b2),where the aliphatic diol (b1) is neopentyl glycol, (B) optionally atleast one further polymer, (C) optionally at least one additive and/or(D) optionally at least one reinforcer, in an extruder to obtain anextrudate (E) comprising components (A) and optionally (B), (C) and/or(D), b) pelletizing the extrudate (E) obtained in step a) to obtain apelletized material (G) comprising components (A) and optionally (B),(C) and/or (D), c) micronizing the pelletized material (G) obtained instep c) to obtain the sinter powder (SP).
 25. The method according toclaim 24, wherein the sinter powder (SP) obtained in step c) is thenheat-treated in a step d) at a temperature T_(T) to obtain aheat-treated sinter powder (SP).
 26. A method of producing a shapedbody, comprising the steps of: a) providing a layer of a sinter powder(SP) according to claim 15, b) optionally heating the layer up to amaximum of 2 K below the melting temperature T_(M) of the sinter powder(SP), where the melting temperature T_(M) is determined by means ofdynamic scanning calorimetry according to the description, c) exposingthe layer of the sinter powder (SP) provided in step a) or optionallyheated in step b), preferably in a sintering method, more preferably ina selective laser sintering method, in a high-speed sintering (HSS)method or a multijet fusion (MJF) method.
 27. A shaped body obtainableby a method according to claim
 26. 28. The use of a sinter powder (SP)according to claim 15 in a sintering method, preferably in a selectivelaser sintering method, in a high-speed sintering (HSS) method or amultijet fusion (MJF) method.